The present invention relates to a vehicular steering controller for calculating, based on a target path of a vehicle, an operation amount of an actuator that controls steering of a tire angle.
Japanese Laid-Open Patent Publication No. 2012-51441 discloses a device for automatically switching manual steering to automatic steering. This device switches steering from automatic steering to manual steering when a user's steering angle of the steering wheel is greater than or equal to a predetermined value during automatic steering. Thereafter, if the steering angle is less than the predetermined value, the device automatically switches manual steering to automatic steering. After the steering angle of the steering wheel is less than the predetermined value, if the difference between a target path and an actual path of the vehicle is less than or equal to a threshold value, the device automatically switches steering to automatic steering.
The present inventors considered a configuration in which steering is switched to automatic steering when the steering angle of the steering wheel is greater than or equal to the predetermined value. When the steering angle of the steering wheel is greater than or equal to the predetermined value, the steering angle is varied in some cases. Time is required until variation in the tire angle corresponding to variation in the steering angle is reflected in the actual direction of the vehicle. Hence, there is a concern that the target path and the actual path of the vehicle are compared with each other before the variation in the tire angle is reflected in the actual path. As a result of such comparison, if it is determined that the difference between these paths is less than or equal to the threshold value, there is a concern that the automatic steering does not match with intended steering of a user. Hence, in a state where the steering angle of the steering wheel is greater than or equal to the predetermined value, if only a fact that the difference between the paths is less than or equal to the threshold value is employed as an execution condition for switching the automatic steering, behavior of the vehicle gives the user a feeling of strangeness when the automatic steering processing is started.
This device switches between manual steering for operating an actuator which steering-controls the tire angle based on an input operation performed on the steering wheel and automatic steering for operating the actuator independently from the input operation performed on the steering wheel. In this case, when manual steering is switched to automatic steering, the device switches a contribution ratio from 0% to 100%. The contribution ratio is the ratio in which an operation amount calculated for automatic steering contributes to an operation of the actuator. In a device that executes processing for increasing the contribution ratio when automatic steering is carried out, the above-described actual circumstance that behavior of a vehicle gives a user a feeling of strangeness is also generally in common. For example, the above-described actual circumstance also applies to a device that switches the contribution ratio to a predetermined value that is less than 100% when automatic steering is carried out.